This is a safety and pharmacokinetic study of nevirapine in HIV-positive pregnant women and their newborns. The mother is given a single dose of nevirapine in labor and the infant a single dose of nevirapine, 2.0 mg/kg orally, between 48 and 72 hours post delivery. Pharmacokinetic (PK) study samples are drawn from the infant at 1, 2, 4, 6, 8, 12, 24, 48, and 72 hours post dose. After birth, the mother and infant may be admitted to the GCRC to stay while the intensive PK samples are drawn from infant and the mother/infant pair are observed.